Numerous active compounds cannot be administered orally for a variety of reasons including: a) their rapid enzymatic and metabolic degradation; b) their chemical and biological instability; c) their low solubility in aqueous medium, and/or d) their limited permeability in the gastrointestinal tract.
Exemplary active compounds presenting one or more these problems include glycosaminoglycan (GAG)-type macromolecules, such as heparin and its derivatives, LMWH (Low Molecular Weight Heparins), pentasacharides (like fondaparinux), ULMWH (Ultra Low Molecular Weight Heparins), Chondroitin sulfate, Dermatan sulfate, etc. GAG-type macromolecules are highly sulfated un-branched polysaccharides that comprise repeating disaccharides of an uronic acid (iduronic or glucuronic) linked to an aminosugar (glucosamine or galactosamine). The building blocks of these macromolecules are as follows:
